Facebook is kind of like... dead when it comes to art. I post stuff there, but it feels like even when people "like" stuff they're not engaged?
People on Twitter, Tumblr, and Instagram seem way more likely to share and comment instead of just and move on.
My comics tumblr is just links to my main website, tapastic, and patreon when I post a new page and a place to gather concept art and fanart. Like Shazz said, it's not a great place to BUILD a following, but kind of just a bonus for people already interested in your work. I was kind of lucky in that I already had a following on their for my illustrations, so some of those people crossed over into following my comic on Tumblr as well... but I still feel like more people have found my comic-tumblr through tapastic or my comic's website and not the other way around.
Twitter is probably my favorite social media site. It's a great place to talk to other artists and your readers/fans. I'm not really into #hashtag stuff... but I like to go on twitter and make jokes and tell funny stories about what I'm up to on an almost daily basis. And I share whatever art I'm workin on, too... but it's kind of more of a place for talking and making connections in my opinion.
Instagram is the opposite. I like to just post pictures there without a lot of chatter. You can't link to things, so it's kind of just it's own self contained gallery.
The last thing I can think of that might help you is making a little update frame? That way you can post to social media without posting WIP or full pages by just posting a snippet of the finished page with a link to wherever you want to send people.
Whenever I have a new page up I post one of these around to let people know.